Folded camera

ABSTRACT

A folded camera that includes two light folding elements such as prisms and an independent lens system, located between the two prisms, which includes an aperture stop and a lens stack. The lens system may be moved on one or more axes independently of the prisms to provide autofocus and/or optical image stabilization for the camera. The shapes, materials, and arrangements of the refractive lens elements in the lens stack may be selected to capture high resolution, high quality images while providing a sufficiently long back focal length to accommodate the second prism.

PRIORITY INFORMATION

This application is a continuation of U.S. patent application Ser. No.17/371,732, filed Jul. 9, 2021, which is a continuation of U.S. patentapplication Ser. No. 16/264,463, filed Jan. 31, 2019, now U.S. Pat. No.11,061,213, which claims benefit of priority of U.S. ProvisionalApplication Ser. No. 62/627,645 entitled “FOLDED CAMERA” filed Feb. 7,2018, the content of which are incorporated by reference herein in theirentirety.

BACKGROUND Technical Field

This disclosure relates generally to camera systems, and morespecifically to small form factor camera and lens systems.

Description of the Related Art

The advent of small, mobile multipurpose devices such as smartphones andtablet or pad devices has resulted in a need for high-resolution, smallform factor cameras that are lightweight, compact, and capable ofcapturing high resolution, high quality images at low F-numbers forintegration in the devices. However, due to limitations of conventionalcamera technology, conventional small cameras used in such devices tendto capture images at lower resolutions and/or with lower image qualitythan can be achieved with larger, higher quality cameras. Achievinghigher resolution with small package size cameras generally requires useof a photosensor with small pixel size and a good, compact imaging lenssystem. Advances in technology have achieved reduction of the pixel sizein photosensors. However, as photosensors become more compact andpowerful, demand for compact imaging lens systems with improved imagingquality performance has increased. In addition, there are increasingexpectations for small form factor cameras to be equipped with higherpixel count and/or larger pixel size image sensors (one or both of whichmay require larger image sensors) while still maintaining a moduleheight that is compact enough to fit into portable electronic devices.Thus, a challenge from an optical system design point of view is toprovide an imaging lens system that is capable of capturing highbrightness, high resolution images under the physical constraintsimposed by small form factor cameras.

SUMMARY OF EMBODIMENTS

Embodiments of the present disclosure may provide a folded camera thatmay, for example, be used in small form factor cameras. Embodiments of afolded camera are described that include two light folding elements(e.g., prisms) and an independent lens system located between the twoprisms that includes an aperture stop and lens elements with refractivepower mounted in a lens barrel. The prisms and lens system maycollectively be referred to as an optical system. The prisms provide a“folded” optical axis for the camera, for example to reduce the Z-heightof the camera. The lens system includes a lens stack including one ormore refractive lens elements mounted in a lens barrel, and an aperturestop located at or in front of a first lens element in the stack. Afirst prism redirects light from an object field from a first axis (AX1) to the lens system on a second axis (AX 2). The lens element(s) inthe lens stack receive the light through the aperture stop and refractthe light to a second prism that redirects the light onto a third axis(AX 3) on which a photosensor of the camera is disposed. The redirectedlight forms an image plane at or near the surface of the photosensor.

The shapes, materials, and arrangements of the refractive lens elementsin the lens stack may be selected to capture high resolution, highquality images while providing a sufficiently long back focal length toaccommodate the second prism. Parameters and relationships of the lensesin the lens stack, including but not limited to lens shape, thickness,geometry, position, materials, spacing, and the surface shapes ofcertain lens elements, may be selected at least in part to reduce,compensate, or correct for optical aberrations and lens artifacts andeffects across the field of view. In some embodiments, arrangements ofpower distribution, lens shapes, prism form factors, and lens materialsmay be selected to ensure that embodiments of the lens system providelow F-number (e.g., <=2.4), 3× optical zoom, and high resolutionimaging.

The lens system may be configured in the camera to move on one or moreaxes independently of the prisms. The camera may include an actuatorcomponent configured to move the lens system on (parallel to) the secondaxis (AX 2) relative to and independently of the prisms to provideautofocus functionality for the camera. In some embodiments, theactuator may instead or also be configured to move the lens system onone or more axes perpendicular to the second axis (AX 2) relative to andindependently of the prisms to provide optical image stabilization (OIS)functionality for the camera. In some embodiments, one or both of theprisms may be translated with respect to the second axis (AX 2)independently of the lens system and/or tilted with respect to thesecond axis (AX 2) independently of the lens system, for example toprovide OIS functionality for the camera or to shift the image formed atan image plane at the photosensor.

In some embodiments, the lens system may include a lens stack consistingof four lens elements with refractive power, in order from the objectside to the image side of the camera: a first lens element with positiverefractive power; a second lens element with positive refractive power;a third lens element with negative refractive power and an asphericshape to correct chromatic aberration and field curvature; and a fourthlens element with a meniscus shape to correct field curvature andprovide a low F-number.

In some embodiments, the lens system may include a lens stack consistingof five lens elements with refractive power, in order from the objectside to the image side of the camera: a first lens element with positiverefractive power; a second lens element with positive refractive power;a third lens element with negative refractive power and an asphericshape to correct chromatic aberration and field curvature; a fourthaspheric lens element configured as an air-space doublet with the thirdlens element that assists in the aberration correction provided by thethird lens element; and a fifth lens element with a meniscus shape tocorrect field curvature and provide a low F-number.

An aperture stop may be located in the lens system at the first lenselement for controlling the brightness of the camera. Note that thepower order, shape, or other optical characteristics of the refractivelens elements may be different in some embodiments, and some embodimentsmay include more or fewer refractive lens elements. In some embodiments,the folded camera may include an infrared (IR) filter to reduce oreliminate interference of environmental noise on the photosensor. The IRfilter may, for example, be located between the second prism and thephotosensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates components of a folded camera with two light foldingelements and an independent lens system, according to some embodiments.

FIG. 1B illustrates movements of the lens system relative to the lightfolding elements in a camera as illustrated in FIG. 1A, according tosome embodiments.

FIG. 2 is a cross-sectional illustration of a folded camera with fourrefractive lens elements in the lens system, according to someembodiments.

FIG. 3 is a diagram illustrating a lens system that includes fourrefractive lens elements, according to some embodiments.

FIG. 4A is a graph illustrating the modulation transfer function (MTF)for a lens system as illustrated in FIG. 3 at infinity conjugate.

FIG. 4B shows longitudinal spherical aberration, astigmatic fieldcurves, and distortion for a lens system as illustrated in FIG. 3 atinfinity conjugate.

FIG. 5A is a graph illustrating the modulation transfer function (MTF)for a lens system as illustrated in FIG. 3 at macro conjugate.

FIG. 5B shows longitudinal spherical aberration, astigmatic fieldcurves, and distortion for a lens system as illustrated in FIG. 3 atmacro conjugate.

FIG. 6 is a cross-sectional illustration of a folded camera with fiverefractive lens elements in the lens system, according to someembodiments.

FIG. 7 is a diagram illustrating a lens system that includes fiverefractive lens elements, according to some embodiments.

FIG. 8A is a graph illustrating the modulation transfer function (MTF)for a lens system as illustrated in FIG. 7 at infinity conjugate.

FIG. 8B shows longitudinal spherical aberration, astigmatic fieldcurves, and distortion for a lens system as illustrated in FIG. 7 atinfinity conjugate.

FIG. 9A is a graph illustrating the modulation transfer function (MTF)for a lens system as illustrated in FIG. 7 at macro conjugate.

FIG. 9B shows longitudinal spherical aberration, astigmatic fieldcurves, and distortion for a lens system as illustrated in FIG. 7 atmacro conjugate.

FIG. 10 is a diagram illustrating a lens system that includes fourrefractive lens elements, according to some embodiments.

FIG. 11A is a graph illustrating the modulation transfer function (MTF)for a lens system as illustrated in FIG. 10 .

FIG. 11B shows longitudinal spherical aberration, astigmatic fieldcurves, and distortion for a lens system as illustrated in FIG. 10 .

FIG. 12 is a flowchart of a method for capturing images usingembodiments of a camera as illustrated in FIGS. 1 through 11B, accordingto some embodiments.

FIG. 13 illustrates an example computer system that may be used inembodiments.

This specification includes references to “one embodiment” or “anembodiment.” The appearances of the phrases “in one embodiment” or “inan embodiment” do not necessarily refer to the same embodiment.Particular features, structures, or characteristics may be combined inany suitable manner consistent with this disclosure.

“Comprising.” This term is open-ended. As used in the appended claims,this term does not foreclose additional structure or steps. Consider aclaim that recites: “An apparatus comprising one or more processor units. . . ”. Such a claim does not foreclose the apparatus from includingadditional components (e.g., a network interface unit, graphicscircuitry, etc.).

“Configured To.” Various units, circuits, or other components may bedescribed or claimed as “configured to” perform a task or tasks. In suchcontexts, “configured to” is used to connote structure by indicatingthat the units/circuits/components include structure (e.g., circuitry)that performs those task or tasks during operation. As such, theunit/circuit/component can be said to be configured to perform the taskeven when the specified unit/circuit/component is not currentlyoperational (e.g., is not on). The units/circuits/components used withthe “configured to” language include hardware—for example, circuits,memory storing program instructions executable to implement theoperation, etc. Reciting that a unit/circuit/component is “configuredto” perform one or more tasks is expressly intended not to invoke 35U.S.C. § 112, sixth paragraph, for that unit/circuit/component.Additionally, “configured to” can include generic structure (e.g.,generic circuitry) that is manipulated by software and/or firmware(e.g., an FPGA or a general-purpose processor executing software) tooperate in manner that is capable of performing the task(s) at issue.“Configure to” may also include adapting a manufacturing process (e.g.,a semiconductor fabrication facility) to fabricate devices (e.g.,integrated circuits) that are adapted to implement or perform one ormore tasks.

“First,” “Second,” etc. As used herein, these terms are used as labelsfor nouns that they precede, and do not imply any type of ordering(e.g., spatial, temporal, logical, etc.). For example, a buffer circuitmay be described herein as performing write operations for “first” and“second” values. The terms “first” and “second” do not necessarily implythat the first value must be written before the second value.

“Based On.” As used herein, this term is used to describe one or morefactors that affect a determination. This term does not forecloseadditional factors that may affect a determination. That is, adetermination may be solely based on those factors or based, at least inpart, on those factors. Consider the phrase “determine A based on B.”While in this case, B is a factor that affects the determination of A,such a phrase does not foreclose the determination of A from also beingbased on C. In other instances, A may be determined based solely on B.

DETAILED DESCRIPTION

Embodiments of a folded camera are described that include two lightfolding elements (e.g., prisms) and an independent lens system locatedbetween the two prisms that includes an aperture stop and lens elementswith refractive power mounted in a barrel. The prisms and lens systemmay collectively be referred to as an optical system. FIG. 1Aillustrates components of a folded camera 100 with two prisms 141 and142, and an independent lens system 110, according to some embodiments.The prisms 141 and 142 provide a “folded” optical axis for the camera100, for example to reduce the Z-height of the camera 100. The lenssystem 110 includes a lens stack 114 including one or more refractivelens elements mounted in a lens barrel 112, and an aperture stop 130located at or in front of a first lens element in the stack 114. A firstprism 141 redirects light from an object field from a first axis (AX 1)to the lens system 110 on a second axis (AX 2). The lens element(s) inthe lens stack 114 receive the light through the aperture stop 130 andrefract the light to a second prism 142 that redirects the light onto athird axis (AX 3) on which a photosensor 120 of the camera 100 isdisposed. The redirected light forms an image at an image plane 121 ator near the surface of the photosensor 120.

The shapes, materials, and arrangements of the refractive lens elementsin the lens stack 114 may be selected to capture high resolution, highquality images while providing a sufficiently long back focal length toaccommodate the second prism 142. The camera 100 may, but does notnecessarily, include an infrared (IR) filter 150, for example locatedbetween the second prism 142 and the photosensor 120.

FIG. 1B illustrates movements of the lens system 110 independently ofand relative to the prisms 141 and 142 in a camera 100 as illustrated inFIG. 1A, according to some embodiments. In some embodiments, the camera100 may include an actuator 160 component or components configured tomove the lens system 110 on (parallel to) the second axis (AX 2)relative to and independently of the prisms 141 and 142 to provideautofocus functionality for the camera 100. In some embodiments, theactuator 160 component(s) may instead or also be configured to move thelens system 110 on one or more axes orthogonal to the second axis (AX 2)relative to and independently of the prisms 141 and 142 to provideoptical image stabilization (OIS) functionality for the camera 100.While not shown, in some embodiments, one or both of the prisms 141 and142 may be translated with respect to the second axis (AX 2)independently of the lens system 110 and/or tilted with respect to thesecond axis (AX 2) independently of the lens system 110, for example toprovide OIS functionality for the camera 100 or to shift the imageformed at an image plane 121 at the photosensor 120.

Embodiments of a lens system for a folded camera as described herein areconfigured with a long back focal length (the distance from the lastrefractive lens element to the image plane) to provide space for asecond light folding element (e.g., a second prism). In addition,arrangements of power distribution, lens shapes, prism form factors, andlens materials may be selected to ensure that embodiments of the lenssystem provide low F-number (e.g., <=2.4), 3× optical zoom, and highresolution imaging.

Embodiments of the folded camera as described herein may be implementedin a small package size while still capturing sharp, high-resolutionimages, making embodiments of the camera suitable for use in smalland/or mobile multipurpose devices such as cell phones, smartphones, pador tablet computing devices, laptop, netbook, notebook, subnotebook, andultrabook computers, and so on. FIG. 13 illustrates an example devicethat may include one or more small form factor cameras that useembodiments of the camera as described herein. However, note thataspects of the camera (e.g., the lens system, prisms, and photosensor)may be scaled up or down to provide cameras with larger or smallerpackage sizes. In addition, embodiments of the camera may be implementedas stand-alone digital cameras. In addition to still (single framecapture) camera applications, embodiments of the camera may be adaptedfor use in video camera applications.

FIG. 2 is a cross-sectional illustration of a folded camera with fourrefractive lens elements in the lens system, according to someembodiments. FIG. 2 shows an example camera 200 including two prisms 241and 242 that “fold” the optical axis of the camera 200 and an exampleembodiment of a lens system 210 with four refractive lens elements201-204 located between the prisms 241 and 242. The lens elements201-204 are mounted in a lens barrel 212, with an aperture stop 230located at or in front of the first (object side) lens element 201.While embodiments are generally described as using prisms to fold theoptical axis, other methods may be used to fold the optical axis,including but not limited to mirrors. The first prism 241 folds theoptical axis from a first axis (AX 1) that is parallel to the incominglight direction to a second axis (AX 2) that is orthogonal to theincoming light direction. The second prism 242 folds the optical axisfrom the second axis (AX 2) that is orthogonal to the incoming lightdirection to a third axis (AX 3) that is parallel to the incoming lightdirection.

The camera 200 also includes a photosensor 220, and may also include anoptional infrared (IR) filter. A camera 200 including an embodiment ofthe lens system 210 as illustrated in FIG. 2 may, for example, beimplemented in portable electronic devices such as mobile phones andtablets. Embodiments of the lens system 210 may provide a low F-number(<=2.4), 3× optical zoom, and high resolution imaging.

In some embodiments, the camera 200 may include an actuator 260component or components configured to move the lens system 210 on(parallel to) the second axis (AX 2) relative to and independently ofthe prisms 241 and 242 to provide autofocus functionality for the camera200. In some embodiments, the actuator 260 component(s) may instead oralso be configured to move the lens system 210 on one or more axesorthogonal to the second axis (AX 2) relative to and independently ofthe prisms 241 and 242 to provide optical image stabilization (OIS)functionality for the camera 200. Various types of mechanical, magnetic,or other actuator technology may be used in various embodiments. In someembodiments, one or both of the prisms 241 and 242 may be translatedwith respect to the second axis (AX 2) independently of the lens system210 and/or tilted with respect to the second axis (AX 2) independentlyof the lens system 210, for example to provide OIS functionality for thecamera 200 or to shift the image formed at an image plane 221 at thephotosensor 220.

As shown in the example of FIG. 2 , embodiments of the lens system 210may include four lens elements 201-204 with refractive power. Note,however, that some embodiments may include more or fewer refractive lenselements. Some embodiments of the lens system 210 may provide a 35 mmequivalent focal length in the range of 80-200 mm and less than 6.5 mmof Z-height to fit in a wide variety of portable electronics devices.With proper arrangement of materials and lens powers, embodiments of thelens system 210 are capable of capturing high brightness photographs orvideo frames with near diffraction-limited image quality.

As illustrated in the example camera 200 of FIG. 2 , the lens system 210may include four lens elements 201-204 with refractive power, in orderfrom the object side to the image side of the camera 200: a first lenselement 201 with positive refractive power; a second lens element 202with positive refractive power; a third lens element 203 with negativerefractive power and an aspheric shape to correct chromatic aberrationand field curvature; and a fourth lens element 204 with a meniscus shapeto correct field curvature and provide a low F-number. At least one ofthe refractive lens elements may be formed of lightweight polymer orplastic material. At least two of the refractive lens elements may beformed of materials with different Abbe numbers. An aperture stop 230may be located in the lens system 210 at the first lens element 201 forcontrolling the brightness of the camera 200. Note that the power order,shape, or other optical characteristics of the refractive lens elementsmay be different in some embodiments, and some embodiments may includemore or fewer refractive lens elements.

In some embodiments, the camera 200 includes two right-angle prisms 241and 242 to change the direction of the light passing through the camera200. In some embodiments, one or both of the prisms may be shifted ortilted relative to the position of the lens system 210 to provideautofocus and/or OIS functionality for the camera 200. In someembodiments, the aperture stop 230 is integrated in the lens system 210to control brightness in the camera 200. Integrating the stop 230 in thelens system 210 enables the lens system 210 to be isolated from andmoved independently with relation to the prisms 241 and 242. In someembodiments, the aperture stop 230 may be fixed; the diameter of thestop 230 may be chosen according to system requirements. However, insome embodiments, the aperture stop may be adjustable.

In some embodiments, the camera 200 includes an IR filter 250, forexample located between light folding element 242 and photosensor 220,to reduce or eliminate interference of environmental noises on thesensor 220.

Camera 200 Z-height is sensitive to barrel 212 diameter. In someembodiments, to provide a desired Z-height for a particular camera 200application, the structure of the barrel 212 may be modified. Forexample, in various embodiments of a camera 200, the barrel 212 may betruncated, may be tapered, may be single-sided, and/or may have areverse assembly structure.

FIG. 3 is a diagram illustrating a lens system that includes fourrefractive lens elements, according to some embodiments. A camera 300may include a photosensor 320, two light folding elements (e.g., prisms341 and 342), and an independent lens system 310 located between the twoprisms 341 and 342 that includes an aperture stop 330 and lens elementswith refractive power mounted in a lens barrel. The prisms provide a“folded” optical axis for the camera, for example to reduce the Z-heightof the camera. The lens system 310 includes an aperture stop 330 tocontrol system brightness while maintaining an integrated lens systemthat is independent of the two prisms 341 and 342. The camera 300 may,but does not necessarily, include an infrared (IR) filter 350, forexample located between the second prism 342 and the photosensor 320.

The example lens system 310 shown in FIG. 3 includes a lens stackconsisting of four refractive elements 301-304 that provide a lowF-number (<=F/2.4), 3× optical zoom, and high resolution imaging. Lenses301 and 302 both have positive refractive power for light convergingwhile splitting the spherical aberration contributions of each lens 301and 302. Lens 303 has negative refractive power, and an aspheric shapeto correct chromatic aberration and field curvature. Lens 304 is ameniscus lens to correct field curvature and enable low F-numberoperation of the camera 300. In some embodiments, lens 304 may have lowpositive refractive power.

In some embodiments, the lens system 310 may be shifted along AX 2independently of the two prisms 341 and 342 to allow refocusing of thelens system 310 between Infinity conjugate and Macro conjugate. In someembodiments, the lens system 310 may be shifted on one or more axesorthogonal to AX 2 to provide OIS functionality for the camera 300. Invarious embodiments, lens elements 301, 302, 303, and/or 304 may beround/circular or rectangular, or some other shape. Note that in variousembodiments, a lens system 310 may include more or fewer refractive lenselements, and the lens elements may be configured or arrangeddifferently.

In some embodiments, one or both of the prisms 341 and 342 may beshifted independently of the lens system 310 along one or more axes by amechanical actuator mechanism to facilitate autofocus functionality forthe lens system 310 between Infinity conjugate and Macro conjugate. Insome embodiments, one or both of the prisms 341 and 342 may betranslated with respect to the second axis (AX 2) independently of thelens system 310 and/or tilted with respect to the second axis (AX 2)independently of the lens system 342 by a mechanical actuator mechanism,for example to provide OIS functionality for the camera 300 or to shiftthe image formed at an image plane 321 at the photosensor 320.

FIG. 4A is a graph illustrating the modulation transfer function (MTF)for a lens system as illustrated in FIG. 3 at infinity conjugate. FIG.4B shows longitudinal spherical aberration, astigmatic field curves, anddistortion for a lens system as illustrated in FIG. 3 at infinityconjugate.

FIG. 5A is a graph illustrating the modulation transfer function (MTF)for a lens system as illustrated in FIG. 3 at macro conjugate. FIG. 5Bshows longitudinal spherical aberration, astigmatic field curves, anddistortion for a lens system as illustrated in FIG. 3 at macroconjugate.

FIG. 6 is a cross-sectional illustration of a folded camera with fiverefractive lens elements in the lens system, according to someembodiments. FIG. 6 shows an example camera 600 including two prisms 641and 642 that “fold” the optical axis of the camera 600 and an exampleembodiment of a lens system 610 with five refractive lens elements601-605 located between the prisms 641 and 642. The lens elements601-605 are mounted in a lens barrel 612, with an aperture stop 630located at or in front of the first (object side) lens element 601.While embodiments are generally described as using prisms to fold theoptical axis, other methods may be used to fold the optical axis,including but not limited to mirrors. The first prism 641 folds theoptical axis from a first axis (AX 1) that is parallel to the incominglight direction to a second axis (AX 2) that is orthogonal to theincoming light direction. The second prism 642 folds the optical axisfrom the second axis (AX 2) that is orthogonal to the incoming lightdirection to a third axis (AX 3) that is parallel to the incoming lightdirection.

The camera 600 also includes a photosensor 620, and may also include anoptional infrared (IR) filter. A camera 600 including an embodiment ofthe lens system 610 as illustrated in FIG. 6 may, for example, beimplemented in portable electronic devices such as mobile phones andtablets. Embodiments of the lens system 610 may provide a low F-number(<=2.4), 3× optical zoom, and high resolution imaging.

In some embodiments, the camera 600 may include an actuator 660component or components configured to move the lens system 610 on(parallel to) the second axis (AX 2) relative to and independently ofthe prisms 641 and 642 to provide autofocus functionality for the camera600. In some embodiments, the actuator 660 component(s) may instead oralso be configured to move the lens system 610 on one or more axesorthogonal to the second axis (AX 2) relative to and independently ofthe prisms 641 and 642 to provide optical image stabilization (OIS)functionality for the camera 600. Various types of mechanical, magnetic,or other actuator technology may be used in various embodiments. In someembodiments, one or both of the prisms 641 and 642 may be translatedwith respect to the second axis (AX 2) independently of the lens system610 and/or tilted with respect to the second axis (AX 2) independentlyof the lens system 610, for example to provide OIS functionality for thecamera 600 or to shift the image formed at an image plane 621 at thephotosensor 620.

As shown in the example of FIG. 6 , embodiments of the lens system 610may include five lens elements 601-605 with refractive power. Note,however, that some embodiments may include more or fewer refractive lenselements. Some embodiments of the lens system 610 may provide a 35 mmequivalent focal length in the range of 80-600 mm and less than 6.5 mmof Z-height to fit in a wide variety of portable electronics devices.With proper arrangement of materials and lens powers, embodiments of thelens system 610 are capable of capturing high brightness photographs orvideo frames with near diffraction-limited image quality.

As illustrated in the example camera 600 of FIG. 6 , the lens system 610may include five lens elements 601-605 with refractive power, in orderfrom the object side to the image side of the camera 600: a first lenselement 601 with positive refractive power; a second lens element 602with positive refractive power; a third lens element 603 with negativerefractive power and an aspheric shape to correct chromatic aberrationand field curvature; a fourth aspheric lens element 604 configured as anair-space doublet with lens element 603 that assists in the aberrationcorrection provided by lens element 603; and a fifth lens element 605with a meniscus shape to correct field curvature and provide a lowF-number. At least one of the refractive lens elements may be formed oflightweight polymer or plastic material. At least two of the refractivelens elements may be formed of materials with different Abbe numbers. Anaperture stop 630 may be located in the lens system 610 at the firstlens element 601 for controlling the brightness of the camera 600. Notethat the power order, shape, or other optical characteristics of therefractive lens elements may be different in some embodiments, and someembodiments may include more or fewer refractive lens elements.

In some embodiments, the camera 600 includes two right-angle prisms 641and 642 to change the direction of the light passing through the camera600. In some embodiments, one or both of the prisms may be shifted ortilted relative to the position of the lens system 610 to provideautofocus and/or OIS functionality for the camera 600. In someembodiments, the aperture stop 630 is integrated in the lens system 610to control brightness in the camera 600. Integrating the stop 630 in thelens system 610 enables the lens system 610 to be isolated from andmoved independently with relation to the prisms 641 and 642. In someembodiments, the aperture stop 630 may be fixed; the diameter of thestop 630 may be chosen according to system requirements. However, insome embodiments, the aperture stop may be adjustable.

In some embodiments, the camera 600 includes an IR filter 650, forexample located between light folding element 642 and photosensor 620,to reduce or eliminate interference of environmental noises on thesensor 620.

Camera 600 Z-height is sensitive to barrel 612 diameter. In someembodiments, to provide a desired Z-height for a particular camera 600application, the structure of the barrel 612 may be modified. Forexample, in various embodiments of a camera 600, the barrel 612 may betruncated, may be tapered, may be single-sided, and/or may have areverse assembly structure.

FIG. 7 is a diagram illustrating a lens system that includes fiverefractive lens elements in the lens system, according to someembodiments. A camera 700 may include a photosensor 720, two lightfolding elements (e.g., prisms 741 and 742), and an independent lenssystem 710 located between the two prisms 741 and 742 that includes anaperture stop 730 and lens elements with refractive power mounted in alens barrel. The prisms provide a “folded” optical axis for the camera,for example to reduce the Z-height of the camera. The lens system 710includes an aperture stop 730 to control system brightness whilemaintaining an integrated lens system that is independent of the twoprisms 741 and 742. The camera 700 may, but does not necessarily,include an infrared (IR) filter 750, for example located between thesecond prism 742 and the photosensor 720.

The example lens system 710 shown in FIG. 7 includes a lens stackconsisting of five refractive elements 701-705 that provide a lowF-number (<=F/2.4), 3× optical zoom, and high resolution imaging. Lenses701 and 702 both have positive refractive power for light convergingwhile splitting the spherical aberration contributions of each lens 701and 702. Lens 703 has negative refractive power, and an aspheric shapeto correct chromatic aberration and field curvature. Lens 704 works asan air space doublet with lens 703 to provide aberration correction.Lens 705 is a meniscus lens to correct field curvature and enable lowF-number operation of the camera 700. In some embodiments, lens 705 mayhave low positive refractive power.

In some embodiments, the lens system 710 may be shifted along AX 2independently of the two prisms 741 and 742 to allow refocusing of thelens system 710 between Infinity conjugate and Macro conjugate. In someembodiments, the lens system 710 may be shifted on one or more axesorthogonal to AX 2 to provide OIS functionality for the camera 700. Invarious embodiments, lens elements 701, 702, 703, 704, and/or 705 may beround/circular or rectangular, or some other shape. Note that in variousembodiments, a lens system 710 may include more or fewer refractive lenselements, and the lens elements may be configured or arrangeddifferently.

In some embodiments, one or both of the prisms 741 and 742 may beshifted independently of the lens system 710 along one or more axes by amechanical actuator mechanism to facilitate autofocus functionality forthe lens system 710. In some embodiments, one or both of the prisms 741and 742 may be translated with respect to the second axis (AX 2)independently of the lens system 710 and/or tilted with respect to thesecond axis (AX 2) independently of the lens system 742 by a mechanicalactuator mechanism, for example to provide OIS functionality for thecamera 700 or to shift the image formed at an image plane 721 at thephotosensor 720.

FIG. 8A is a graph illustrating the modulation transfer function (MTF)for a lens system as illustrated in FIG. 7 at infinity conjugate. FIG.8B shows longitudinal spherical aberration, astigmatic field curves, anddistortion for a lens system as illustrated in FIG. 7 at infinityconjugate.

FIG. 9A is a graph illustrating the modulation transfer function (MTF)for a lens system as illustrated in FIG. 7 at macro conjugate. FIG. 9Bshows longitudinal spherical aberration, astigmatic field curves, anddistortion for a lens system as illustrated in FIG. 7 at macroconjugate.

FIG. 10 is a diagram illustrating a lens system that includes fourrefractive lens elements, according to some embodiments. A camera 1000may include a photosensor 1020, two light folding elements (e.g., prisms1041 and 1042), and an independent lens system 1010 located between thetwo prisms 1041 and 1042 that includes an aperture stop 1030 and lenselements with refractive power mounted in a lens barrel. The prismsprovide a “folded” optical axis for the camera, for example to reducethe Z-height of the camera. The lens system 1010 includes an aperturestop 1030 to control system brightness while maintaining an integratedlens system that is independent of the two prisms 1041 and 1042. Thecamera 1000 may, but does not necessarily, include an infrared (IR)filter 1050, for example located between the second prism 1042 and thephotosensor 1020.

The example lens system 1010 shown in FIG. 10 includes a lens stackconsisting of four refractive elements 1001-1004 that provide a lowF-number (<=F/2.4), 3× optical zoom, and high resolution imaging. Lens1001 has positive refractive power for light converging while beingaspheric to control spherical aberration. Lens 1002 has negativerefractive power and has an Abbe number that is less than 30. Lens 1003is a meniscus lens, and has a concave object-side surface in theparaxial region and a convex image-side surface in the paraxial region.Lens 1004 is a meniscus lens to correct field curvature and enable lowF-number operation of the camera 1000.

In some embodiments, the lens system 1010 may be shifted along thesecond axis (AX 2) independently of the two prisms 1041 and 1042 toallow refocusing of the lens system 1010 between Infinity conjugate andMacro conjugate. In some embodiments, the lens system 1010 may beshifted on one or more axes orthogonal to AX 2 to provide OISfunctionality for the camera 1000. In various embodiments, lens elements1001, 1002, 1003, and/or 1004 may be round/circular or rectangular, orsome other shape. Note that in various embodiments, a lens system 1010may include more or fewer refractive lens elements, and the lenselements may be configured or arranged differently.

In some embodiments, one or both of the prisms 1041 and 1042 may beshifted independently of the lens system 1010 along one or more axes bya mechanical actuator mechanism to facilitate autofocus functionalityfor the lens system 1010. In some embodiments, one or both of the prisms1041 and 1042 may be translated with respect to the second axis (AX 2)independently of the lens system 1010 and/or tilted with respect to thesecond axis (AX 2) independently of the lens system 1042 by a mechanicalactuator mechanism, for example to provide OIS functionality for thecamera 1000 or to shift the image formed at an image plane 1021 at thephotosensor 1020.

FIG. 11A is a graph illustrating the modulation transfer function (MTF)for a lens system as illustrated in FIG. 10 . FIG. 11B showslongitudinal spherical aberration, astigmatic field curves, anddistortion for a lens system as illustrated in FIG. 10 .

Example Flowchart

FIG. 12 is a flowchart of a method for capturing images usingembodiments of a camera as illustrated in FIGS. 1 through 11B, accordingto some embodiments. As indicated at 1900, light from an object field infront of the camera is received at a first light folding element such asa prism on a first axis. As indicated at 1910, the light is redirectedby the first prism to a second axis. As indicated at 1920, the light isreceived through an aperture at a first lens of a lens system on thesecond axis. As indicated at 1930, the light is refracted by one or morelens elements of the lens system on the second axis to a second lightfolding element such as a prism. As indicated at 1940, the light isredirected by the second light folding element to a third axis. Asindicated at 1950, the light forms an image at an image plane at or nearthe surface of a sensor module on the third axis. As indicated at 1960,the image is captured by the photosensor. The lens system is independentof the first and second prisms. The camera may include an actuatorcomponent configured to move the lens system on one or more axesindependently of the prisms to provide autofocus and/or OISfunctionality for the camera.

While not shown in FIG. 12 , in some embodiments, the light may passthrough an infrared filter that may for example be located between thesecond light folding element and the photosensor. In some embodiments,the aperture stop may be fixed; the diameter of the stop may be chosenaccording to system requirements. However, in some embodiments, theaperture stop may be adjustable. In some embodiments, one or both of theprisms are fixed. However, in some embodiments, one or both of theprisms may be shifted or tilted with respect to the second axis andindependently of the lens system.

In some embodiments, the components of the lens system referred to inFIG. 12 may be configured as illustrated in any of FIG. 2, 3, 6, 7 or 10. However, note that variations on the examples given in the Figures arepossible while achieving similar optical results.

Example Computing Device

FIG. 13 illustrates an example computing device, referred to as computersystem 2000, that may include or host embodiments of a camera with alens system as illustrated in FIGS. 1 through 12 . In addition, computersystem 2000 may implement methods for controlling operations of thecamera and/or for performing image processing of images captured withthe camera. In different embodiments, computer system 2000 may be any ofvarious types of devices, including, but not limited to, a personalcomputer system, desktop computer, laptop, notebook, tablet or paddevice, slate, or netbook computer, mainframe computer system, handheldcomputer, workstation, network computer, a camera, a set top box, amobile device, a wireless phone, a smartphone, a consumer device, videogame console, handheld video game device, application server, storagedevice, a television, a video recording device, a peripheral device suchas a switch, modem, router, or in general any type of computing orelectronic device.

In the illustrated embodiment, computer system 2000 includes one or moreprocessors 2010 coupled to a system memory 2020 via an input/output(I/O) interface 2030. Computer system 2000 further includes a networkinterface 2040 coupled to I/O interface 2030, and one or moreinput/output devices 2050, such as cursor control device 2060, keyboard2070, and display(s) 2080. Computer system 2000 may also include one ormore cameras 2090, for example one or more cameras as described abovewith respect to FIGS. 1 through 12 , which may also be coupled to I/Ointerface 2030, or one or more cameras as described above with respectto FIGS. 1 through 12 along with one or more other cameras such asconventional wide-field cameras.

In various embodiments, computer system 2000 may be a uniprocessorsystem including one processor 2010, or a multiprocessor systemincluding several processors 2010 (e.g., two, four, eight, or anothersuitable number). Processors 2010 may be any suitable processor capableof executing instructions. For example, in various embodimentsprocessors 2010 may be general-purpose or embedded processorsimplementing any of a variety of instruction set architectures (ISAs),such as the x86, PowerPC, SPARC, or MIPS ISAs, or any other suitableISA. In multiprocessor systems, each of processors 2010 may commonly,but not necessarily, implement the same ISA.

System memory 2020 may be configured to store program instructions 2022and/or data 2032 accessible by processor 2010. In various embodiments,system memory 2020 may be implemented using any suitable memorytechnology, such as static random access memory (SRAM), synchronousdynamic RAM (SDRAM), nonvolatile/Flash-type memory, or any other type ofmemory. In the illustrated embodiment, program instructions 2022 may beconfigured to implement various interfaces, methods and/or data forcontrolling operations of camera 2090 and for capturing and processingimages with integrated camera 2090 or other methods or data, for exampleinterfaces and methods for capturing, displaying, processing, andstoring images captured with camera 2090. In some embodiments, programinstructions and/or data may be received, sent or stored upon differenttypes of computer-accessible media or on similar media separate fromsystem memory 2020 or computer system 2000.

In one embodiment, I/O interface 2030 may be configured to coordinateI/O traffic between processor 2010, system memory 2020, and anyperipheral devices in the device, including network interface 2040 orother peripheral interfaces, such as input/output devices 2050. In someembodiments, I/O interface 2030 may perform any necessary protocol,timing or other data transformations to convert data signals from onecomponent (e.g., system memory 2020) into a format suitable for use byanother component (e.g., processor 2010). In some embodiments, I/Ointerface 2030 may include support for devices attached through varioustypes of peripheral buses, such as a variant of the Peripheral ComponentInterconnect (PCI) bus standard or the Universal Serial Bus (USB)standard, for example. In some embodiments, the function of I/Ointerface 2030 may be split into two or more separate components, suchas a north bridge and a south bridge, for example. Also, in someembodiments some or all of the functionality of I/O interface 2030, suchas an interface to system memory 2020, may be incorporated directly intoprocessor 2010.

Network interface 2040 may be configured to allow data to be exchangedbetween computer system 2000 and other devices attached to a network2085 (e.g., carrier or agent devices) or between nodes of computersystem 2000. Network 2085 may in various embodiments include one or morenetworks including but not limited to Local Area Networks (LANs) (e.g.,an Ethernet or corporate network), Wide Area Networks (WANs) (e.g., theInternet), wireless data networks, some other electronic data network,or some combination thereof. In various embodiments, network interface2040 may support communication via wired or wireless general datanetworks, such as any suitable type of Ethernet network, for example;via telecommunications/telephony networks such as analog voice networksor digital fiber communications networks; via storage area networks suchas Fibre Channel SANs, or via any other suitable type of network and/orprotocol.

Input/output devices 2050 may, in some embodiments, include one or moredisplay terminals, keyboards, keypads, touchpads, scanning devices,voice or optical recognition devices, or any other devices suitable forentering or accessing data by computer system 2000. Multipleinput/output devices 2050 may be present in computer system 2000 or maybe distributed on various nodes of computer system 2000. In someembodiments, similar input/output devices may be separate from computersystem 2000 and may interact with one or more nodes of computer system2000 through a wired or wireless connection, such as over networkinterface 2040.

As shown in FIG. 16 , memory 2020 may include program instructions 2022,which may be processor-executable to implement any element or action tosupport integrated camera 2090, including but not limited to imageprocessing software and interface software for controlling camera 2090.In some embodiments, images captured by camera 2090 may be stored tomemory 2020. In addition, metadata for images captured by camera 2090may be stored to memory 2020.

Those skilled in the art will appreciate that computer system 2000 ismerely illustrative and is not intended to limit the scope ofembodiments. In particular, the computer system and devices may includeany combination of hardware or software that can perform the indicatedfunctions, including computers, network devices, Internet appliances,PDAs, wireless phones, pagers, video or still cameras, etc. Computersystem 2000 may also be connected to other devices that are notillustrated, or instead may operate as a stand-alone system. Inaddition, the functionality provided by the illustrated components mayin some embodiments be combined in fewer components or distributed inadditional components. Similarly, in some embodiments, the functionalityof some of the illustrated components may not be provided and/or otheradditional functionality may be available.

Those skilled in the art will also appreciate that, while various itemsare illustrated as being stored in memory or on storage while beingused, these items or portions of them may be transferred between memoryand other storage devices for purposes of memory management and dataintegrity. Alternatively, in other embodiments some or all of thesoftware components may execute in memory on another device andcommunicate with the illustrated computer system 2000 via inter-computercommunication. Some or all of the system components or data structuresmay also be stored (e.g., as instructions or structured data) on acomputer-accessible medium or a portable article to be read by anappropriate drive, various examples of which are described above. Insome embodiments, instructions stored on a computer-accessible mediumseparate from computer system 2000 may be transmitted to computer system2000 via transmission media or signals such as electrical,electromagnetic, or digital signals, conveyed via a communication mediumsuch as a network and/or a wireless link. Various embodiments mayfurther include receiving, sending or storing instructions and/or dataimplemented in accordance with the foregoing description upon acomputer-accessible medium. Generally speaking, a computer-accessiblemedium may include a non-transitory, computer-readable storage medium ormemory medium such as magnetic or optical media, e.g., disk orDVD/CD-ROM, volatile or non-volatile media such as RAM (e.g. SDRAM, DDR,RDRAM, SRAM, etc.), ROM, etc. In some embodiments, a computer-accessiblemedium may include transmission media or signals such as electrical,electromagnetic, or digital signals, conveyed via a communication mediumsuch as network and/or a wireless link.

The methods described herein may be implemented in software, hardware,or a combination thereof, in different embodiments. In addition, theorder of the blocks of the methods may be changed, and various elementsmay be added, reordered, combined, omitted, modified, etc. Variousmodifications and changes may be made as would be obvious to a personskilled in the art having the benefit of this disclosure. The variousembodiments described herein are meant to be illustrative and notlimiting. Many variations, modifications, additions, and improvementsare possible. Accordingly, plural instances may be provided forcomponents described herein as a single instance. Boundaries betweenvarious components, operations and data stores are somewhat arbitrary,and particular operations are illustrated in the context of specificillustrative configurations. Other allocations of functionality areenvisioned and may fall within the scope of claims that follow. Finally,structures and functionality presented as discrete components in theexample configurations may be implemented as a combined structure orcomponent. These and other variations, modifications, additions, andimprovements may fall within the scope of embodiments as defined in theclaims that follow.

What is claimed is:
 1. An optical system, comprising: a first lightfolding element; a second light folding element; and a lens systemcomprising one or more lens elements located between the first lightfolding element and the second light folding element; wherein the firstlight folding element redirects light from an object field from a firstaxis to the lens system on a second axis; wherein the one or more lenselements in the lens system refract the light to the second lightfolding element; wherein the second light folding element redirects thelight from the second axis onto a third axis to form an image of theobject field at an image plane; wherein the lens system is movable ontwo or more axes independently of the first and second light foldingelements, and wherein F-number of the lens system is less than or equalto 2.4, a 35 mm equivalent focal length of the lens system is in a range80-200 mm, and Z-height of the lens system <6.5 mm.
 2. The opticalsystem as recited in claim 1, wherein the lens system provides a 3×optical zoom.
 3. The optical system as recited in claim 1, wherein atleast one of the first and second light folding elements is a prism. 4.The optical system as recited in claim 1, wherein the lens system ismovable on the second axis to provide autofocus functionality for theoptical system.
 5. The optical system as recited in claim 1, wherein thelens system is movable on one or more axes orthogonal to the second axisto provide optical image stabilization functionality for the opticalsystem.
 6. The optical system as recited in claim 1, wherein one or bothof the light folding elements can be translated with respect to thesecond axis independently of the lens system.
 7. The optical system asrecited in claim 1, wherein one or both of the light folding elementscan be tilted with respect to the second axis independently of the lenssystem.
 8. A camera, comprising: a photosensor configured to capturelight projected onto a surface of the photosensor; a first light foldingelement that redirects light received from an object field from a firstaxis to a second axis; a lens system comprising one or more refractivelens elements that refract the light on the second axis; a second lightfolding element that redirects the light refracted by the lens systemfrom the second axis to a third axis to form an image of the objectfield at an image plane at or near a surface of the photosensor; andwherein F-number of the lens system is less than or equal to 2.4, a 35mm equivalent focal length of the lens system is in a range 80-200 mm,and Z-height of the lens system <6.5 mm.
 9. The camera as recited inclaim 8, wherein the lens system is movable on two or more axesindependently of the first and second light folding elements.
 10. Thecamera as recited in claim 8, further comprising an actuator componentconfigured to move the lens system on two or more axes independently ofthe first and second light folding elements.
 11. The camera as recitedin claim 8, wherein the lens system is movable on the second axis toprovide autofocus functionality for the camera.
 12. The camera asrecited in claim 8, wherein the lens system is movable on one or moreaxes orthogonal to the second axis to provide optical imagestabilization functionality for the camera.
 13. The camera as recited inclaim 8, wherein the camera further includes one or more actuatorcomponents configured to translate or tilt one or both of the lightfolding elements with respect to the second axis independently of thelens system.
 14. The camera as recited in claim 8, wherein the lenssystem provides a 3× optical zoom.
 15. A device to capture one or moreimages, comprising: one or more processors; one or more cameras; and amemory comprising program instructions executable by at least one of theone or more processors to control operations of the one or more cameras;wherein at least one of the one or more cameras is a camera comprising:a photosensor configured to capture light projected onto a surface ofthe photosensor; a first light folding element that redirects lightreceived from an object field from a first axis to a second axis; a lenssystem comprising one or more refractive lens elements that refract thelight on the second axis; a second light folding element that redirectsthe light refracted by the lens system from the second axis to a thirdaxis to form an image of the object field at an image plane at or near asurface of the photosensor; and wherein F-number of the lens system isless than or equal to 2.4, a 35 mm equivalent focal length of the lenssystem is in a range 80-200 mm, and Z-height of the lens system <6.5 mm.16. The device as recited in claim 15, further comprising an actuatorcomponent configured to move the lens system on two or more axesindependently of the first and second light folding elements.
 17. Thedevice as recited in claim 15, wherein the camera further includes oneor more actuator components configured to translate or tilt one or bothof the light folding elements with respect to the second axisindependently of the lens system.
 18. The device as recited in claim 15,wherein the lens system is movable on one or more axes orthogonal to thesecond axis to provide optical image stabilization functionality for thecamera.
 19. The device as recited in claim 15, wherein the lens systemis movable on the second axis to provide autofocus functionality for thecamera.
 20. The device as recited in claim 15, wherein the lens systemprovides a 3× optical zoom.